Milwaukee pH58 Max pH/ORP
#8 in Pen testersFull review
A pen for pool and water-treatment work that needs ORP as well as pH. For pH alone, cheaper pens are as accurate.
Amazon $219.65$219.65
±0.05 pH2-pointORP
3.1/5
A well-made pocket tester from a lab brand, for anyone who already uses Hanna buffers and electrodes. The Apera PH60 does more for less.
- ±0.05 pHAccuracy
- 3-pointCalibration
- WaterproofWaterproof
- YesReplaceable probe
Check price at Amazon$179.99
Price checked November 8, 2026. As an Amazon Associate we earn from qualifying purchases.
Pros
- Three-point calibration and 0.01 pH resolution
- Replaceable electrode
- Floats if it is dropped
Cons
- One-year warranty
- Costs twice the Apera PH60 for looser accuracy
How it scores
The rating comes from 6 measured or published factors, each scored 0-100 against fixed reference points for its type. How we rank explains each one.
Specifications
| Model number | HI98128 |
|---|---|
| pH measurement | |
| Accuracy | ±0.05 pH |
| Resolution | 0.01 pH |
| Range | -2 to 16 pH |
| Calibration | 3-point |
| Temperature compensation | Yes |
| Other readings | |
| Conductivity (EC/TDS) | No |
| ORP | No |
| Salinity | No |
| Build | |
| Replaceable probe | Yes |
| Waterproof rating | Waterproof |
| Battery life | 300 hours |
| Weight | 100 g |
| Meter warranty | 1 year |
Alternatives in this type
Apera PH20
#9 in Pen testersFull review
A cheap, waterproof pen for pools, aquariums and drinking water. Pick it when 0.1 pH is close enough.
Amazon $56.65$56.65
±0.1 pH3-pointNone
Milwaukee pH55 Pro
#11 in Pen testersFull review
A low-cost pen with a replaceable electrode, for pools, gardens and aquariums. The Apera PH60 is more accurate for a little more.
Amazon $77.90$77.90
±0.1 pH2-pointNone
Compare
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